Quantum-Enhanced Metrology for Molecular Symmetry Violation Using Decoherence-Free Subspaces

Phys Rev Lett. 2023 Nov 10;131(19):193602. doi: 10.1103/PhysRevLett.131.193602.

Abstract

We propose a method to measure time-reversal symmetry violation in molecules that overcomes the standard quantum limit while leveraging decoherence-free subspaces to mitigate sensitivity to classical noise. The protocol does not require an external electric field, and the entangled states have no first-order sensitivity to static electromagnetic fields as they involve superpositions with zero average lab-frame projection of spins and dipoles. This protocol can be applied with trapped neutral or ionic species, and can be implemented using methods that have been demonstrated experimentally.